Conventionally known lighting fixtures include a projector type headlight including a light source, a reflector configured to reflect light from the light source, and a projector lens configured to project the light reflected by the reflector forward. Examples of such a projector type headlight may include those disclosed in Japanese Patent No. 4459702 and Japanese Translation of PCT Patent Application Publication No. 2012-524958 (or US2012/039083A1 corresponding thereto).
The vehicle lighting fixture disclosed e former publication can include two light source units 30A and 30B disposed behind a projector lens 22 to be bilaterally symmetric in a left-right direction. The light source unit 30A can include a light emitting element 24A and a reflector 26A, and the light source unit 30B can include a light emitting element 24B and a reflector 26B. Here, the reflectors 26A and 26B are integrally formed. With this configuration, the light emitted from the respective light emitting elements 24A and 24B can be reflected by the corresponding reflectors 26A and 26B to secure a sufficient amount of light to be projected. (See, for example, paragraphs 0035 to 0038, 0055 to 0056, and 0062, and FIGS. 2 and 6(a) of Japanese Patent No. 4459702.)
The vehicle lighting fixture disclosed in the latter publication can include two light sources 5 and 6, two reflectors 2 having two reflecting surfaces 2a and 2b integrally formed to achieve a low-beam illumination function. (See, for example, paragraphs 0047 and 0059 to 0060, and FIGS. 1, 4, and 5 of Japanese Translation of PCT Patent Application Publication No. 2012-524958.) The vehicle lighting fixture in the latter publication can further include a lower lighting unit including alight source 7 and a second reflector 3 below the reflector 2 to also achieve a high-beam illumination function. (See, for example, paragraphs 0048 and 0061 to 0062, and FIGS. 2, 4, and 5.)
The hide lighting units of these publications are configured to include a light source and a reflector by one-to-one correspondence, and these publications have no mention about the technology in which the light from a first one of the light sources can be reflected to a second one of the reflector that does correspond to the first light source. Furthermore, it is uncertain how the light from the light sources can be effectively utilized. The resulting light distribution pattern would have illumination unevenness.
In consideration of these points in association with the conventional vehicle lighting fixtures, the present inventors conducted a trial production of a vehicle lighting fixture 100 illustrated in FIG. 1. The vehicle lighting fixture 100 was configured to include two light sources and reflect light from one of the light sources by a noncorresponding reflector out of reflectors.
Specifically, the vehicle lighting unit 100 of FIG. 1 can include the two light sources 110 and 120, two reflectors 130 (not shown) and 140, a projector lens 150 disposed in front of the reflectors 130 (not shown) and 140, and a shade 160 disposed below the reflectors 130 (not shown) and 140 for shielding the light reflected by the reflectors 130 (not shown) and 140 to control the light distribution. FIG. 2 shows the shade 160 having a top surface 162 having been subjected to aluminum vapor deposition. As a result, the top surface 162 can have an aluminum deposited film formed thereon to serve as a mirror-finished reflecting surface.
Note that in FIG. 1 the reflector 130 configured to cover the light source 110 is omitted for facilitating the understanding the internal structure and only the reflector 140 configured to cover the light source 120 is illustrated as a representative.
In this configuration, when the light sources 110 and 120 are turned on, the light emitted from the light sources 110 and 120 can be incident on the corresponding reflectors 130 (not shown) and 140 and reflected by the same forward basically, then enter the projector lens 150 to be projected forward and slightly downward. As a result of such a light distribution, the light from the light sources 110 and 120 can form a light distribution pattern illustrated in the drawing (a) of FIG. 3 having a bright-dark border at its upper end edge. In this case, however, the light distribution pattern illustrated in the drawing (a) of FIG. 3 is formed to include uneven luminance regions 200 and 202 on left and right sides.
In order to identify the cause of the uneven luminance regions 200 and 202, when only the light source 110 was turned on, a light distribution pattern as illustrated in the drawing (b) of FIG. 3 was formed. The light distribution pattern illustrated in the drawing (b) of FIG. 3 includes a remarkable uneven luminance region 204, and it was considered that the uneven luminance region 204 caused the uneven luminance region 200.
The inventors further examined the test results and found that when only the one light source 110 was turned on, the light from the light source 110 could also be incident on and reflected by the noncorresponding reflector 140 as the inventors had assumed, and then, part of the reflected light could be incident on the projector lens 150 but another part of the reflected light could be incident on a side portion 164 of the shade 160 and then further reflected as shown in FIG. 1. As a result, the light flux including these parts could be projected through the projector lens 150. The projected light could form a light distribution pattern as illustrated in the drawing (c) of FIG. 3. Note that the light distribution pattern illustrated in the drawing (c) of FIG. 3 is drawn by the light intensity magnified a hundred times to understand the light distribution pattern more clearly.
As can be seen from the drawing (c) of FIG. 3, the light is locally concentrated near the uneven luminance region 204. Then, the inventors focused attention on the shape of the shade 160 and found that the side portions 164 and 166 were, as can be seen from FIG. 2, configured to be flat as same as the center portion 163 of the top surface 162 and this configuration might be a cause for generating the uneven luminance region 204, and in turn, the uneven luminance regions 200 and 202.